1. Field of the Invention
The present invention is in the field of hydraulic accumulators and pulse dampeners and pertains more particularly to a method of making a pressure vessel for an accumulator or pulse dampener device of the type employing an elastomeric bladder by steps which include heat deforming after installation of the bladder.
2. The Prior Art
Accumulators and pulse dampener devices of the type incorporating an elastomeric bladder member dividing the interior of the pressure vessel into two discrete chambers in communication, respectively, with an oil port and a gas charging port, are well known. Numerous methods of making such devices have been practiced.
Specifically, the pressure vessel may be comprised of two preformed half shell members, each member normally including a hemispheric closed end and an open mouth portion.
In accordance with a typical fabrication, the elastomeric bladder member is secured in one shell half and thereafter the mouth portions of the shell halves are secured together to form the pressure vessel. The shell halves may be forged or cast. The operation of forming the shell halves and securing them together is expensive and time consuming.
Attempts have been made to form pressure vessels from cylindrical starting components by hot spinning one end of the cylinder into the desired hemispherical configuration, thereafter emplacing a bladder member supported on a metallic mounting ring at an intermediate position within the partially formed cylinder, and finally hot spinning the remaining open cylindrical end to the desired hemispheric configuration. The ends of the cylinder are typically not closed but, rather, apertures remain which are machined and within which are mounted the oil port assembly and the gas charging valve assembly.
While the formation of pressure vessels by hot spinning steps provides a convenient and inexpensive manufacturing procedure, a high incidence of damage to the bladder member has been experienced at the gas charging end of the vessel during the formation by hot spinning of the hemispherical end in which the gas charging aperture is formed.